US4791455A - Color electrophotographic apparatus and method of cleaning a photosensitive medium - Google Patents

Color electrophotographic apparatus and method of cleaning a photosensitive medium Download PDF

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Publication number
US4791455A
US4791455A US07/014,691 US1469187A US4791455A US 4791455 A US4791455 A US 4791455A US 1469187 A US1469187 A US 1469187A US 4791455 A US4791455 A US 4791455A
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Prior art keywords
photosensitive medium
toner
fur brush
cleaning
set forth
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US07/014,691
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English (en)
Inventor
Hajime Yamamoto
Hidenori Kunishige
Yuji Takashima
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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Priority claimed from JP61029243A external-priority patent/JPS62187377A/ja
Priority claimed from JP61077151A external-priority patent/JPS62232675A/ja
Priority claimed from JP61204106A external-priority patent/JPS6358463A/ja
Priority claimed from JP61234817A external-priority patent/JPS6388572A/ja
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD., A CORP. OF JAPAN reassignment MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD., A CORP. OF JAPAN ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: KUNISHIGE, HIDENORI, TAKASHIMA, YUJI, YAMAMOTO, HAJIME
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
    • G03G21/0005—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium
    • G03G21/0035—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium using a brush; Details of cleaning brushes, e.g. fibre density

Definitions

  • the present invention relates to a cleaning device which can be applied to an apparatus for producing hard copies of color images such as color copiers, color printers and so forth.
  • the invention also is concerned with a multi-color printing apparatus which incorporates the cleaning device.
  • FIG. 1 schematically shows a known color electrophotographic apparatus of a type which is disclosed in Japanese Patent Laid-Open No. 95456/1985.
  • This apparatus has a photosensitive medium 1 made of a selenium-tellurium (Se--Te) alloy and adapted to rotate in the direction shown by an arrow, a corona charger 2 for electrostatically charging the photosensitive medium, a laser beam scanner 3, developing units 4 to 7 which accommodate toners of yellow (Y), magenta (M), cyan (C) and black (Bk) respectively.
  • a reference numeral 8 denotes a sheet of paper on which a copy image is to be formed.
  • the apparatus further has a charge-eliminating lamp 9, a corona transfer device 10, a toner fusing device 11, a cleaning blade 12 and a charge eliminating lamp 13 for initializing the surface potential of the photosensitive medium after the transfer.
  • the photosensitive medium 1 is positively charged by the corona charger 2, and a scanning exposure is conducted by means of the laser beam scanner 3 so as to expose the medium to the yellow picture signal, thus forming a negative electrostatic latent image. More specifically, the portions of the area on the photosensitive medium corresponding to the picture and line portions of the original image are exposed so that the surface potential is attenuated in these portions.
  • the electrostatic latent image thus formed is then inverted and developed by the developing unit 4 which contains the yellow toner Y, whereby an yellow toner image is formed on the photosensitive medium 1.
  • the developing unit 4 containing the yellow toner is connected to an electric power supply, while other developing units 5 to 7 are inoperative. Then, the whole area of the photosensitive medium is irradiated with light from the charge eliminating lamp 13, so that the electrostatic latent image for the yellow color is extinguished.
  • the process including charging, exposure, development and charge elimination by light which are the same as those explained in connection with yellow color is conducted repeatedly for each of the magenta, cyan and black colors.
  • Toner images of yellow, magenta, cyan and black colors are thus formed on the photosensitive medium 1.
  • the electrostatic latent images are neutralized by the charge eliminating lamp 9, and these toner images are transferred onto an ordinary sheet of paper by means of the corona charger 10.
  • the toner images transferred to the paper are then fixed by application of heat by means of the toner fusing device 11.
  • toner particles remaining on the photosensitive medium 1 are removed by the cleaning blade 12, so that the photosensitive medium becomes ready for the formation of the next image.
  • the known apparatus shown in FIG. 1 suffers from a disadvantage in that the purities of colors of the copy image are degraded as the number of the printing cycles grow large, due to the fact that the toners of respective colors in the developing units are contaminated by the toners of different colors.
  • the present inventors have made an intense study to clarify the cause of the contamination of the toners, and reached a conclusion which will be explained hereinunder with reference to FIG. 2A.
  • a cleaning blade 14 is held in contact with the photosensitive medium 15 so as to clean the surface of the photosensitive medium while collecting the toner particles.
  • a bulk 16 of toner which is about 2 mm thick and 5 mm wide, is formed on the end of the cleaning blade 14.
  • the cleaning blade 14 is moved away from the photosensitive medium 15 when the image is to be formed on the photosensitive medium 15.
  • the bulk 16 of the toner possibly remains on the surface of the photosensitive medium 15 so tha it is conveyed to the developing unit 17 so as to contaminate the toner in this developing unit.
  • an object of the present invention is to provide a cleaning device which is improved in such a way that no bulk of toner is left on the photosensitive medium when the cleaning device is moved away from the photosensitive medium.
  • a cleaning device for use in a color electrophotographic apparatus in which a photosensitive medium is made to rotate for a plurality of times so as to conduct repetitional cycles each including charging, exposure and development, thereby forming toner images of different colors on the photosensitive medium, the cleaning device comprising:
  • a conductive fur brush for cleaning the surface of the photosensitive medium so as to remove any toner remaining on the surface of the photosensitive medium
  • a driving mechanism for placing the fur brush in contact with the photosensitive medium during cleaning and for keeping the same away from the photosensitive medium when the cleaning is not conducted.
  • FIG. 1 is a schematic illustration of a known color electrophotographic apparatus
  • FIGS. 2A and 2B are illustrations of operation of the known apparatus illustrating problems which are encountered by the known apparatus
  • FIG. 3 is an illustration of the basic arrangement of an embodiment of the cleaning device of the present invention.
  • FIG. 4 is an illustration of the basic arrangement of an improved cleaning device in accordance with the present invention.
  • FIG. 5 is an illustration of the principle of operation of a color electrophotographic printer as an embodiment of a multi-color printing apparatus of the invention
  • FIG. 6 is an illustration of the principle of operation of a color electrophotographic printer as an improved embodiment of a multi-color printing apparatus of the invention
  • FIG. 7 is an illustration of the principle of operation of a color electrophotographic printer as another improved embodiment of a multi-color printing apparatus of the invention.
  • FIG. 8 is an illustration of the principle of operation of a color electrophotographic printer as a further improved embodiment of a multi-color printing apparatus of the invention.
  • the known color electrophotographic apparatus incorporating a blade-type cleaning device encounters a problem in that a bulk of the toner remains on the photosensitive medium after the cleaning device is moved away from the photosensitive medium.
  • This imposes a serious problem particularly in systems in which a color copy image is obtained by directly superposing toner images on the photosensitive medium, because the bulk of toner remaining on the photosensitive medium causes contamination of the respective toners due to mixing of toners of different colors.
  • a voltage of a polarity reverse to the charging polarity of the toner is applied to a conductive fur brush so that the fur brush electrostatically attracts and adsorbs the toner. As a consequence, the toner is completely removed from the surface of the photosensitive medium without remaining on the medium surface.
  • the apparatus is preferably equipped with a toner collecting roller which is adapted to collect the toner from the fur brush.
  • a toner collecting roller which is adapted to collect the toner from the fur brush.
  • the toner collecting roller can collect even the toner particles which have entered the core region of the brush.
  • the cleaning power of the fur brush is recovered to such an extent that the fur brush is always put into use in an almost new or fresh state, so that the fur brush can stand a long use without suffering from any degradation in the cleaning effect.
  • the color print produced by an apparatus incorporating a fur brush of the type described above is defective particularly when the humidity of the ambient air is high. This is attributable to the fact that, when the humidity of the air is high, the efficiency of the transfer of the toner from the photosensitive medium to the paper is lowered, resulting in a cleaning failure.
  • the inventors have confirmed that the toner remaining on the photosensitive medium has been negatively charged by the negative transferring corona through the paper the resistance value of which has been reduced due to absorption of moisture. Such negatively charged toner cannot be removed by the fur brush which is charged so as to attract positively charged toner.
  • the negatively charged toner is charged into the original polarity by a corona charger before the photosensitive medium is cleaned, so that the toner is electrostatically attracted by the conductive fur brush.
  • the toner can be completely removed by the fur brush even when the transfer efficiency is low due to high humidity of the ambient air.
  • the corona charging of the negatively-charged toner into the original polarity may be effected by the main charger through one full rotation of the photosensitive medium or, alternatively, by an auxiliary charger which is located downstream from the transfer charger but upstream of the fur brush cleaner.
  • the fur brush used in the cleaning device of the invention is made of a conductive material.
  • Any conductive fibers such as acrylic fibers with carbon black dispersed therein, conductive polymeric compounds, carbon fibers and metallic fibers can be used conveniently.
  • the conductive material should have a resistivity which preferably ranges between 10 4 to 10 12 ⁇ cm.
  • the fur brush which is generally designated by a numeral 18, is constituted by a conductive roller 19 and a conductive fur 20 fixed to the surface of the conductive roller 19.
  • the fur brush 18 may be formed by winding on the roller 19 a woven fabric with the fur 20 planted thereon.
  • the fur may be directly planted on the roller 19 electrostatically.
  • a scraper plate 21 is held in contact with the fur brush 18 so as to scrape the toner collected by and attaching to the fur brush 18.
  • a high-voltage D.C. power supply 22 is connected to the fur brush 18 so as to apply a D.C. voltage directly to the fur brush 18.
  • the cleaning device also is provided with a driving solenoid 24 which operates to keep the fur brush 13 in contact with a photosensitive medium 23 during cleaning and to keep the same away from the photosensitive medium 23 when the cleaning is not conducted.
  • a driving solenoid 24 which operates to keep the fur brush 13 in contact with a photosensitive medium 23 during cleaning and to keep the same away from the photosensitive medium 23 when the cleaning is not conducted.
  • the fur brush 18 is pressed onto the photosensitive medium 23 and is rotated at a peripheral speed which is 1.5 to 3 times as high as that of the photosensitive medium, in the direction opposite to the direction of movement of the surface of the photosensitive medium 23.
  • the D.C. voltage applied to the fur brush 18 is of the reverse polarity to that of the charged toner on the photosensitive medium, so that the toner is electrostatically adsorbed by the fur brush 18, thus ensuring a high cleaning effect.
  • the level of the D.C. voltage applied to the fur brush preferably ranges between -100 and -600 V.
  • This cleaning device has a conductive toner collecting roller 26 which is held in contact with the fur brush 25 and a scraper plate 27 which is held in contact with the collecting roller 26 so as to scrape the toner off the collecting roller 26.
  • the scraped toner is swept out by means of a screw 28.
  • the collecting roller 26 is preferably made of a conductive material such as a metal, while a rubbery material such as urethane rubber and silicon rubber, as well as a metal such as phosphor bronze and stainless steel, can be used as the material of the scraper plate 27.
  • the fur brush 25, the collecting roller 26, the scraper plate 27 and the discharge screw 28 are assembled together so as to form a cleaning unit 29.
  • High-voltage D.C. power supplies 30 and 31 are connected to the fur brush 25 and the collecting roller 26 so as to apply D.C. voltages thereto.
  • the cleaning device further includes a driving solenoid 33 which is adapted to press the cleaning unit into contact with the photosensitive medium 32 and to keep the unit 29 away from the photosensitive medium 32 when the cleaning is not being conducted.
  • the fur brush 25 is pressed onto the surface of the photosensitive medium 32 and is rotated at a peripheral speed which is 1.5 to 3 times as high as that of the photosensitive medium 32 in the direction opposite to the direction of movement of the surface of the photosensitive medium 32.
  • the collecting roller 26 is rotated at a peripheral speed which is 1.5 to 3 times as high as that of the fur brush 25, in the direction opposite to the direction of movement of the surface of the latter.
  • the power supply 30 supplies the fur brush 25 with a D.C. voltage which is reverse to that of the charged toner on the photosensitive medium.
  • the D.C. voltage of such a polarity applied to the photosensitive medium enables the fur brush 25 to electrostatically attract the toner on the photosensitive medium 32, thus offering a higher cleaning effect.
  • the D.C. voltage applied to the fur brush 25 preferably ranges between -100 and -600 V with respect to the potential of the surface of the photosensitive medium 32.
  • the power supply 31 supplies the collecting roller 26 with a voltage of the polarity reverse to that of the toner on the photosensitive medium and having an absolute value which is greater than that of the voltage applied to the fur brush 25.
  • the D.C. voltage applied to the collecting roller 26 preferably ranges between -100 and -600 V with respect to the potential of the fur brush 25.
  • the voltage applied to the collecting roller 26 preferably ranges between -400 and - 900 V.
  • the collecting roller often fails to remove the toner completely.
  • the fur brush 25 is moved away from the photosensitive medium 32 after the cleaning and is rotated in the direction opposite to the direction of movement of the surface of the photosensitive medium at a peripheral speed which is 1.5 to 3 times as high as the peripheral speed of the medium, while the collecting roller 26 is rotated in the direction opposite to the direction of movement of the surface of the fur brush 25 at a peripheral speed which is 1.5 to 3 times as high as the peripheral speed of the fur brush 25.
  • the power supply 30 applies a voltage of 0 to -600 V to the fur brush 25.
  • the power supply 31 supplies the collecting roller 26 with a voltage of the polarity reverse to that of the toner and of an absolute value greater than that of the voltage applied to the fur brush 25.
  • the relative voltage applied to the collecting roller 26 is from -100 to -600 V with respect to the potential of the fur brush 25.
  • the voltage applied to the collecting roller is -100 to -600 V when the fur brush 25 is grounded.
  • a fur brush 34 was formed by planting, on a stainless steel roller of 10 mm diameter, a fur of acrylic fibers with carbon dispersed therein (resistivity 10 5 ⁇ cm, length of brush fibers 4 mm, size of wire 10 denier and density 3600 fibers per cm 2 ).
  • Aluminum rollers were used as toner carriers 35, 36 and 37, and thin layers of toner were formed on the surfaces of the toner carriers by means of blades and the toner carriers were positioned to oppose photosensitive medium 38 leaving a gap therebetween.
  • Three types of toners Y, M and C were used.
  • the specifications of the toner carriers and the developing conditions were as follows.
  • Thickness of toner layer on toner carrier 30 ⁇ m
  • Amount of charge on toner +3 ⁇ C/g
  • An amorphous Se--Te photosensitive drum 38 of 100 mm diameter was rotated at a peripheral speed of 75 mm/sec, while charging the surface of the drum to a potential off +800 V by a charger 39 (corona voltage +7 KV).
  • a light-emitting diode 40 having an output power of 7 ⁇ W and wavelength of 670 nm was activated to expose the photosensitive drum 38 to yellow signals through a rod lens array 41, thus forming an electrostatic latent image.
  • the photosensitive drum surface was made to pass through a yellow toner carrier 35 under developing condition so that the latent image was developed with the yellow toner.
  • the surface of the photosensitive drum then passed by the magenta toner carrier 36 and the cyan toner carrier 37 which were not in the developing condition.
  • the toner image on the photosensitive drum 38 was not transferred to a paper in this stage, but the whole surface was irradiated with a charge eliminating lamp 42 and then charged again by a corona charger 39.
  • the photosensitive drum 38 was exposed to a signal light corresponding to magenta from the light-emitting diode 40 and the surface of the drum was made to pass by the magenta toner carrier 36 under the developing condition past the yellow toner carrier 35 under the non-developing condition, so that the latent image corresponding to the magenta color was developed by the magenta toner.
  • the surface of the photosensitive drum then passed by the cyan toner carrier 37 under non-developing condition.
  • the whole surface of the photosensitive drum 38 was irradiated with the light from the charge eliminating lamp 42 so as to erase the electrostatic latent image and was then charged by the corona charger 39.
  • the photosensitive drum 38 was exposed to a signal light corresponding to cyan from the light-emitting diode 40 and the surface of the drum was made to pass by the cyan toner carrier 37 under the developing condition past the yellow toner carrier 35 and the magenta toner carrier 36 under the non-developing condition, so that the latent image corresponding to the cyan color was developed by the cyan toner.
  • the color toner images thus formed on the photosensitive drum 38 were transferred to a sheet of paper 44 by a transfer charger 43 and was then thermally fixed.
  • the charges on the photosensitive drum 38 were eliminated by the charge eliminator 42, and a fur brush 34 was pressed onto the photosensitive medium 38 by means of the driving solenoid 45, for the purpose of cleaning. More specifically, the fur brush 34 was rotated at a peripheral speed of 150 mm/sec and was supplied with a D.C. voltage of -300 V from a D.C. power supply 46, while being pressed onto the photosensitive drum 38 by the driving solenoid 45. After the cleaning, the driving solenoid 45 was activated again to move the fur brush 34 away from the photosensitive element 38. When the fur brush 34 is moved apart from the photosensitive drum 38, both the rotation of the fur brush 34 and the application of the voltage were continued. As a consequence, all the toner on the photosensitive drum 38 was removed. It was also confirmed that no bulk nor line was left on the portion of the surface of the photosensitive drum 38 at which the fur brush 34 left the photosensitive drum 38.
  • the color copy image thus obtained exhibited a maximum density which was as high as 1.7, as well as superior colors without contamination.
  • the color purity was not degraded and no substantial contamination of color was observed even after 30,000 successive copying cycles.
  • Color printing was conducted with the same copying apparatus and the same copying method as Example 1.
  • a cleaning device incorporating a known acrylic fiber fur brush (30 mm diameter and rotated in the direction opposite to the direction of movement of the surface of the photosensitive drum 38 at 1880 mm/sec) with air sucking function was used in place of the conductive fur brush cleaner supplied with D.C. voltage.
  • a bulk of toner and a line of toner were left on the surface of the photosensitive drum 38 after the separation of the fur brush cleaner, as in the case of the apparatus employing a conventional blade cleaner, and toners of colors other than yellow were undesirably introduced into the toner carrier 35.
  • degradation of the color purity was started from the early stages of 20 successive copying cycles.
  • a fur brush 49 was formed by planting, on a stainless steel roller 47 of 10 mm diameter, a fur of acrylic fibers with carbon dispersed therein (resistivity 10 5 ⁇ cm, length of brush fibers 4 mm, size of fibers 10 denier and density 3600 fibers per cm 2 ).
  • a toner collecting roller 50 (20 mm diameter) made of aluminum was held in contact with the fur brush 49 over a contact width of 1 mm and a blade 51 made of phosphor bronze was placed in contact with the collecting roller 50.
  • a screw 52 was disposed so as to be able to sweep out the toner scraped by the blade 51.
  • the fur brush 49, toner collecting roller 50, the blade 51 and the discharge screw 52 were assembled together so as to form a cleaning unit 53.
  • Aluminum rollers were used as toner carriers 54, 55 and 56, and thin layers of toner were formed on the surfaces of the toner carriers by means of blades and the toner carriers were positioned to oppose the photosensitive medium 57 leaving a gap therebetween.
  • Three types of toners Y, M and C were used.
  • the specifications of the toner carriers and the developing conditions were as follows.
  • Peripheral speed 150 mm/sec
  • Thickness of toner layer on toner carrier 30 ⁇ m
  • Amount of charge on toner +3 ⁇ C/g
  • An amorphous Se--Te photosensitive drum 57 of 100 mm diameter as the photosensitive medium was rotated at a peripheral speed of 150 mm/sec, while charging the surface of the drum to a potential of +800 V by a charger 58 (corona voltage +7 KV).
  • a light-emitting diode 59 having an output power of 7 ⁇ W and wavelength of 670 nm was activated to expose the photosensitive drum 57 to yellow signals through a rod lens array 60, thus forming an electrostatic latent image.
  • the photosensitive drum surface was made to pass through the yellow toner carrier 54 under developing condition so that the latent image was developed with the yellow toner.
  • the surface of the photosensitive drum then passed by the magenta toner carrier 55 and the cyan toner carrier 56 which were not in the developing condition.
  • the toner image on the photosensitive drum 57 was not transferred to a paper in this stage, but the whole surface was irradiated with a charge eliminating lamp 61 and then charged again by a corona charger 59.
  • the photosensitive drum 38 was exposed to a signal light corresponding to magenta from the light-emitting diode 59 and the surface of the drum was made to pass by the magenta toner carrier 55 under the developing condition past the yellow toner carrier 54 under the non-developing condition, so that the latent image corresponding to the magenta color was developed by the magenta toner.
  • the surface of the photosensitive drum then passed by the cyan toner carrier 56 under non-developing condition.
  • the whole surface off the photosensitive drum 57 was irradiated with the light from the charge eliminating lamp 61 so as to erase the electrostatic latent image and was then charged by the corona charger 58.
  • the photosensitive drum 38 was exposed to a signal light corresponding to cyan from the light-emitting diode 59 and the surface of the drum was made to pass by the cyan toner carrier 56 under the developing condition past the yellow toner carrier 54 and the magenta toner carrier 55 under the non-developing condition, so that the latent image corresponding to the cyan color was developed by the cyan toner.
  • the color toner images thus formed on the photosensitive drum 38 were transferred to a sheet of paper 63 by a transfer charger 62 and was then thermally fixed.
  • the cleaning unit 53 was pressed onto the photosensitive drum 57 by the action of the driving solenoid 64 so as to clean the photosensitive drum 57.
  • the operating conditions of the fur brush 49 and the collecting roller 50 were as follows.
  • Peripheral speed 225 mm/sec
  • Peripheral speed 450 mm/sec
  • the toner on the photosensitive drum was attracted by the fur brush 49 and a part of the thus attracted toner was collected by the collecting roller 50.
  • the driving solenoid 64 was operated again to move the cleaning unit 53 away from the photosensitive drum 57 and the next printing cycle was started. In this state, the operating conditions of the fur brush 49 and the collecting roller 50 were as follows.
  • Peripheral speed 225 mm/sec
  • Peripheral speed 450 mm/sec
  • the color copy image thus obtained exhibited a maximum density which was as high as 1.7, as well as superior colors without contamination.
  • the color purity was not degraded and no substantial contamination of color was observed even after 30,000 successive copying cycles.
  • a fur brush 65 was formed by winding, on a stainless steel roller of 10 mm diameter, a belt of fur of acrylic fibers with carbon dispersed therein (resistivity 10 5 ⁇ cm, length of brush fibers 4 mm, size of fibers 10 denier and density 3600 fibers per cm 2 ).
  • Example 2 The apparatus used in Example incorporated developing devices 66, 67 and 68 which are of non-contact non-magnetic mono-component type capable of causing the toner to fly under application of a D.C. electric field.
  • Each developing device had an aluminum developing roller on which a thin layer of toner is formed by means of a blade. More specifically, the developing devices 66, 67 and 68 contained toners of yellow (Y), magenta (M) and cyan (C), respectively.
  • the developing devices were disposed around a photosensitive drum 69 such that a constant developing gap is formed between each developing roller and the photosensitive drum 69.
  • Each developing device is provided with a driving mechanism for driving the developing device between a developing position in the vicinity of the photosensitive drum 69 and a non-developing position away from the same.
  • the specifications of the developing device, developing conditions and the physical properties of the toner were the same as those in Example 2.
  • the amorphous Se--Te photosensitive drum 69 of 100 mm diameter as the photosensitive medium was rotated at a peripheral speed of 150 mm/sec, while charging the surface of the drum to a potential of +700 V by a charger 58 (corona voltage +7 KV, grid voltage +850 V).
  • a light-emitting diode 71 having an output power of 7 ⁇ W and wavelength of 670 nm was activated to expose the photosensitive drum 69 to yellow signals through a rod lens array 72, thus forming an electrostatic latent image. Subsequently, the latent image was developed by the yellow developing device 66 which was held in the developing condition.
  • the surface of the photosensitive drum then passed by the magenta developing device 67 and the cyan developing device 68 which were not in the developing condition.
  • the photosensitive drum 69 carrying the Y toner image was charged again by a charger 70 to a surface potential of +850 V.
  • the photosensitive drum 69 was exposed to a signal light corresponding to magenta from the light-emitting diode 71 and the surface of the drum was made to pass by the magenta developing device 67 under the developing condition past the yellow developing device 66 under the non-developing condition, so that the latent image corresponding to the magenta color was developed by the magenta toner.
  • the surface of the photosensitive drum then passed by the cyan developing device 68 under non-developing condition.
  • the photosensitive drum 69 after the development by the magenta color was charged again to the surface potential of 850 V by the charger 70.
  • the photosensitive drum 69 was exposed to a signal light corresponding to cyan from the light-emitting diode 71 and the surface of the drum was made to pass by the cyan developing device 68 under the developing condition past the yellow developing device 66 and the magenta developing device 68 under the nondeveloping condition, so that the latent image corresponding to the cyan color was developed by the cyan toner.
  • the color toner images of Y, M and C colors thus formed on the photosensitive drum 69 were transferred to a sheet of paper 74 by a transfer charger 73 and was then thermally fixed. The transfer efficiency was about 80%. After the transfer, a certain portion of the toner was left on the photosensitive drum 69.
  • the toner remaining on the photosensitive drum 69 had been charged negatively, i.e., to the polarity opposite to the initial polarity. Then, the driving solenoid 75 was activated to press the fur brush 65 onto the surface of the photosensitive drum 69 so as to remove the toner remaining on the latter. This cleaning operation was conducted under the following condition.
  • Peripheral speed 225 mm/sec
  • the color copy image thus formed exhibited a maximum density as high as 1.7 and a high quality without substantial color contamination. No deterioration in the cleaning power nor fogging was observed even after 30,000 repetitional printing cycles.
  • This Example is suitable for use particularly in the case where the polarity of charging of the toner is the same as that of the photosensitive drum 69, i.e., when the copy image is obtained through a negative to positive inversion.
  • this Example enables the production cost and the size of the apparatus to be reduced, because the charger used for the purpose of charging the photosensitive drum is utilized also as the charger for charging the toner on the photosensitive drum to the initial polarity.
  • a fur brush 76 was formed by planting, on a stainless steel roller of 10 mm diameter, a fur of acrylic fibers with carbon dispersed therein (resistivity 10 5 ⁇ cm, length of brush fibers 4 mm, size of fibers 10 denier and density 3600 fibers per cm 2 ).
  • the amorphous Se--Te photosensitive drum 80 of 100 mm diameter as the photosensitive medium was rotated at a peripheral speed of 150 mm/sec, and was charged to a surface potential of +500 V by an auxiliary charger 81 (corona voltage +5 KV). Then, a fur brush 76 was pressed onto the photosensitive drum 80 by the solenoid 82.
  • Peripheral speed 225 mm/sec
  • the surface potential of the photosensitive drum 80 was reduced substantially to 0 V. Then, the photosensitive drum 80 was charged to a surface potential of +700 V by a main charger 83 (scorotron charger having corona voltage of +7 kV and grid voltage of +850 V). A light-emitting diode 84 having an output power of 7 ⁇ W and wavelength of 670 nm was activated to expose the photosensitive drum 80 to yellow signals through a rod lens array 85, thus forming an electrostatic latent image. Subsequently, the latent image was developed by the yellow developing device 77 which was held in the developing condition.
  • a main charger 83 corotron charger having corona voltage of +7 kV and grid voltage of +850 V.
  • a light-emitting diode 84 having an output power of 7 ⁇ W and wavelength of 670 nm was activated to expose the photosensitive drum 80 to yellow signals through a rod lens array 85, thus forming an electrostatic latent image. Subsequently, the la
  • the surface of the photosensitive drum then passed by the magenta developing device 78 and the cyan developing device 79 which were not in the developing condition.
  • the photosensitive drum 80 carrying the Y toner image was charged by the auxiliary charger 81 to a potential of +750 V, and was made to pass by the cleaning device which had been kept away from the photosensitive drum 80. Then, the surface of the photosensitive drum 80 was charged again to +800 V by the main charger 83.
  • the photosensitive drum 80 was exposed to a signal light corresponding to magenta from the light-emitting diode 84 and the surface of the drum was made to pass by the magenta developing device 78 under the developing condition past the yellow developing device 77 under the nondeveloping condition, so that the latent image corresponding to the magenta color was developed by the magenta toner.
  • the surface of the photosensitive drum then passed by the cyan developing device 79 under non-developing condition.
  • the photosensitive drum 80 after the development by the magenta color was charged again to the surface potential of +850 V by the auxiliary charger 81 and, after passing by the cleaning device kept away from the photosensitive drum 80, charged up to +880 V by the main charger 83.
  • the photosensitive drum 80 was exposed to a signal light corresponding to cyan from the light-emitting diode 84 and the surface of the drum was made to pass by the cyan developing device 79 under the developing condition past the yellow developing device 77 and the magenta developing device 78 under the non-developing condition, so that the latent image corresponding to the cyan color was developed by the cyan toner.
  • the color toner images of Y, M and C colors thus formed on the photosensitive drum 80 were transferred to a sheet of paper 87 by a transfer charger 86 and was then thermally fixed. The transfer efficiency was about 80%. After the transfer, a certain portion of the toner was left on the photosensitive drum 80.
  • the toner remaining on the photosensitive drum 69 had been charged negatively, i.e., to the polarity opposite to the initial polarity.
  • the toner still remaining on the photosensitive drum was positively charged by the auxiliary charger 81 and was then subjected to a cleaning operation which was conducted under the following condition.
  • Peripheral speed 225 mm/sec
  • the toner on the photosensitive drum 80 was completely attracted and collected by the fur brush 76.
  • the driving solenoid 82 was operated again to move the fur brush 76 away from the photosensitive drum 80 and the next printing cycle was commenced.
  • This Example is suitable for use particularly in the case where the polarity of charging of the toner is the same as that of the photosensitive drum 69, i.e., when the copy image is obtained through a negative to positive inversion.
  • the auxiliary charger 81 has not only the function for charging the toner remaining on the photosensitive drum 80 to the same polarity as the drum 80 but also a function for assisting the main charger 83 in charging the photosensitive drum. Therefore, the auxiliary charger is preferably operated regardless of whether the cleaning device is used or not.
  • the potential of the photosensitive drum charged by the auxiliary charger 81 becomes higher than the desired surface potential, it becomes difficult to lower the surface potential down to the desired level by the operation of the main charger 83. It is, therefore, critical that the charging of the photosensitive drum 80 by the auxiliary charger 81 is made up to a potential below the desired potential to be obtained and then the charging is effected by the main charger 83 up to the desired potential.
  • the main charger 83 is preferably a scorotron charger which enables the surface potential to be controlled easily.
  • the color image thus formed exhibited a maximum density as high as 1.7 and a superior quality of the copy image without no degradation in the purities of colors. No reduction in the cleaning power nor fogging was observed even after 30,000 repetitional printing cycles.
  • auxiliary charger 81 enables photosensitive mediums of materials which tend to exhibit optical memory or materials which are rather difficult to charge, e.g., selenium-arsenic alloy (As 2 Se 3 ) to be used in a high-speed process without any risk that the photosensitive drum exhibit a too low surface potential.
  • materials which tend to exhibit optical memory or materials which are rather difficult to charge e.g., selenium-arsenic alloy (As 2 Se 3 ) to be used in a high-speed process without any risk that the photosensitive drum exhibit a too low surface potential.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Cleaning In Electrography (AREA)
  • Color Electrophotography (AREA)
US07/014,691 1986-02-13 1987-02-10 Color electrophotographic apparatus and method of cleaning a photosensitive medium Expired - Fee Related US4791455A (en)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
JP61029243A JPS62187377A (ja) 1986-02-13 1986-02-13 クリ−ニング装置
JP61-29243 1986-02-13
JP61077151A JPS62232675A (ja) 1986-04-03 1986-04-03 多色画像記録装置
JP61-77151 1986-04-03
JP61-204106 1986-08-29
JP61204106A JPS6358463A (ja) 1986-08-29 1986-08-29 カラ−電子写真装置
JP61234817A JPS6388572A (ja) 1986-10-02 1986-10-02 カラ−電子写真方法
JP61-234817 1986-10-02

Publications (1)

Publication Number Publication Date
US4791455A true US4791455A (en) 1988-12-13

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Family Applications (1)

Application Number Title Priority Date Filing Date
US07/014,691 Expired - Fee Related US4791455A (en) 1986-02-13 1987-02-10 Color electrophotographic apparatus and method of cleaning a photosensitive medium

Country Status (4)

Country Link
US (1) US4791455A (de)
EP (1) EP0233589B1 (de)
KR (1) KR910008071B1 (de)
DE (1) DE3774722D1 (de)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4913992A (en) * 1989-05-26 1990-04-03 Eastman Kodak Company Method of improving a multi-color electrophotographic image by buffing an image toned with an improved toner
US5083169A (en) * 1988-04-06 1992-01-21 Ricoh Company, Ltd. Device for removing deposits from a photoconductive element of an image recorder which is movable between a cleaning and non-cleaning position
US5237377A (en) * 1991-02-16 1993-08-17 Hitachi Koki Co., Ltd. Cleaning device for dry electrophotographic device
US5253025A (en) * 1990-11-28 1993-10-12 Hitachi, Ltd. Apparatus for fixing a toner image, fixing method and electrophotographic recording equipment
US5281999A (en) * 1992-08-24 1994-01-25 Xerox Corporation Modular highlight color and process color printing machine
US5294962A (en) * 1991-11-08 1994-03-15 Casio Electronics Manufacturing Co., Ltd. Contact-type electroconductive brush for electrically charging an image carrier of an image forming apparatus
US5469247A (en) * 1994-07-05 1995-11-21 Lexmark International, Inc. Toned member cleaning by electrified roller
US5477317A (en) * 1992-08-10 1995-12-19 Xerox Corporation Adaptive exposure color correction
EP0709745A2 (de) 1994-10-31 1996-05-01 Xerox Corporation Eine Vollfarben-Hochgeschwindigkeitsdruckmaschine
US5583629A (en) * 1995-06-29 1996-12-10 Xerox Corporation Color electrophotographic printing machine
US5606408A (en) * 1994-09-30 1997-02-25 Ricoh Company, Ltd. Image forming apparatus and cleaning device therefor
EP0718723A3 (de) * 1994-12-07 1997-11-05 Canon Kabushiki Kaisha Elektrophotographisches Gerät
US6035175A (en) * 1998-07-01 2000-03-07 Xerox Corporation Single revolution clutch with auto-homing feature
US6314266B1 (en) * 1998-03-16 2001-11-06 Canon Kabushiki Kaisha Cleaning apparatus equipped with brush roller, process cartridge, and image forming apparatus
US6548218B1 (en) * 1994-06-22 2003-04-15 Canon Kabushiki Kaisha Magnetic particles for charging means, and electrophotographic apparatus, process cartridge and image forming method including same
US20040052557A1 (en) * 2002-09-17 2004-03-18 Brother Kogyo Kabushiki Kaisha Processing device and image forming apparatus
US20050089788A1 (en) * 2002-09-20 2005-04-28 Fuji Xerox Co., Ltd. Image forming apparatus
US20050226649A1 (en) * 2004-04-07 2005-10-13 Murata Kikai Kabushiki Kaisha Image forming device
US20080008498A1 (en) * 2006-07-05 2008-01-10 Kabushiki Kaisha Toshiba Image forming apparatus and its cleaner unit, and cleaner unit replacement method of the image forming apparatus
US20080298833A1 (en) * 2003-08-26 2008-12-04 Yoshiyuki Kimura Cleaning apparatus for removing toner adhered onto endless belt

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DE3810557A1 (de) * 1987-04-01 1988-10-27 Kentek Information System Vorrichtung zur beseitigung teilchenfoermiger entwicklerrueckstaende von einem fotoleitfaehigem element
US4933721A (en) * 1987-04-07 1990-06-12 Konishirpku Photo Industry Co., Ltd. Image forming apparatus with preconditioning exposure selectively forming a multi-color and mono-color image
US4899198A (en) * 1987-12-29 1990-02-06 Eastman Kodak Company Dual purpose cleaning apparatus
JP2879693B2 (ja) * 1989-01-09 1999-04-05 株式会社リコー 転写ドラムクリーニング方法
US5655203A (en) * 1995-06-07 1997-08-05 Xerox Corporation Non-rotating retracted cleaning brush
KR100370196B1 (ko) * 1999-06-16 2003-01-29 삼성전자 주식회사 습식 전자사진방식 인쇄기의 현상유니트

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Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5083169A (en) * 1988-04-06 1992-01-21 Ricoh Company, Ltd. Device for removing deposits from a photoconductive element of an image recorder which is movable between a cleaning and non-cleaning position
US4913992A (en) * 1989-05-26 1990-04-03 Eastman Kodak Company Method of improving a multi-color electrophotographic image by buffing an image toned with an improved toner
US5253025A (en) * 1990-11-28 1993-10-12 Hitachi, Ltd. Apparatus for fixing a toner image, fixing method and electrophotographic recording equipment
US5237377A (en) * 1991-02-16 1993-08-17 Hitachi Koki Co., Ltd. Cleaning device for dry electrophotographic device
US5294962A (en) * 1991-11-08 1994-03-15 Casio Electronics Manufacturing Co., Ltd. Contact-type electroconductive brush for electrically charging an image carrier of an image forming apparatus
US5477317A (en) * 1992-08-10 1995-12-19 Xerox Corporation Adaptive exposure color correction
US5281999A (en) * 1992-08-24 1994-01-25 Xerox Corporation Modular highlight color and process color printing machine
US6548218B1 (en) * 1994-06-22 2003-04-15 Canon Kabushiki Kaisha Magnetic particles for charging means, and electrophotographic apparatus, process cartridge and image forming method including same
US5469247A (en) * 1994-07-05 1995-11-21 Lexmark International, Inc. Toned member cleaning by electrified roller
US5606408A (en) * 1994-09-30 1997-02-25 Ricoh Company, Ltd. Image forming apparatus and cleaning device therefor
EP0709745A2 (de) 1994-10-31 1996-05-01 Xerox Corporation Eine Vollfarben-Hochgeschwindigkeitsdruckmaschine
EP0718723A3 (de) * 1994-12-07 1997-11-05 Canon Kabushiki Kaisha Elektrophotographisches Gerät
US5583629A (en) * 1995-06-29 1996-12-10 Xerox Corporation Color electrophotographic printing machine
EP0751439A2 (de) 1995-06-29 1997-01-02 Xerox Corporation Elektrophotographischer Farbdrucker
US6314266B1 (en) * 1998-03-16 2001-11-06 Canon Kabushiki Kaisha Cleaning apparatus equipped with brush roller, process cartridge, and image forming apparatus
US6035175A (en) * 1998-07-01 2000-03-07 Xerox Corporation Single revolution clutch with auto-homing feature
US20040052557A1 (en) * 2002-09-17 2004-03-18 Brother Kogyo Kabushiki Kaisha Processing device and image forming apparatus
US7024150B2 (en) * 2002-09-17 2006-04-04 Brother Kogyo Kabushiki Kaisha Separable cleaning device for an image forming apparatus
US20050089788A1 (en) * 2002-09-20 2005-04-28 Fuji Xerox Co., Ltd. Image forming apparatus
US7074540B2 (en) * 2002-09-20 2006-07-11 Fuji Xerox Co., Ltd. Image forming apparatus
US20080298833A1 (en) * 2003-08-26 2008-12-04 Yoshiyuki Kimura Cleaning apparatus for removing toner adhered onto endless belt
US8306469B2 (en) * 2003-08-26 2012-11-06 Ricoh Company, Ltd. Cleaning apparatus for removing toner adhered onto endless belt
US20050226649A1 (en) * 2004-04-07 2005-10-13 Murata Kikai Kabushiki Kaisha Image forming device
US7796918B2 (en) * 2006-07-05 2010-09-14 Kabushiki Kaisha Toshiba Image forming apparatus and its cleaner unit, and cleaner unit replacement method of the image forming apparatus
US20100296839A1 (en) * 2006-07-05 2010-11-25 Kabushiki Kaisha Toshiba Image forming apparatus and its cleaner unit, and cleaner unit replacement method of the image forming apparatus
US20080008498A1 (en) * 2006-07-05 2008-01-10 Kabushiki Kaisha Toshiba Image forming apparatus and its cleaner unit, and cleaner unit replacement method of the image forming apparatus

Also Published As

Publication number Publication date
EP0233589B1 (de) 1991-11-27
DE3774722D1 (de) 1992-01-09
KR910008071B1 (ko) 1991-10-07
KR870008235A (ko) 1987-09-25
EP0233589A1 (de) 1987-08-26

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